Multiple-range calibration for per-pin parametric measurement unit

Abstract

A test equipment system can provide signals to, or receive signals from, a device under test (DUT). The test system can include an output stage with output buffer circuitry that can be locally or externally controlled. An external controller can be used to provide precision input signals and, in response, measure current at a DUT interface node of the system, or measure voltage characteristics of various components inside the system. Using the input signals from the external controller, one or more aspects of the test system can be calibrated. For example, resistances of sense resistors in the output stage can be calibrated using current signals received from the external controller. In another example, buffer offset characteristics can be determined using signals from the external controller to control local drive circuitry of the system.

What is claimed is: 
     
         1 . A test equipment system for providing signals to, or receiving signals from, a device under test (DUT), the system comprising:
 output buffer circuitry configured to provide a DUT signal to the DUT at a DUT interface node in response to a force control signal at a buffer control node;   a first sense resistor coupled to the DUT interface node and the output buffer circuitry;   a first range switch coupled to the first sense resistor and an auxiliary driver input node;   controller circuitry configured to provide the force control signal at the buffer control node; and   an auxiliary control circuit configured to bypass the controller circuitry and selectively provide an auxiliary control signal at one of the buffer control node and the auxiliary driver input node.   
     
     
         2 . The test equipment system of  claim 1 , wherein the auxiliary control circuit is configured to provide the auxiliary control signal as a current signal at the auxiliary driver input node. 
     
     
         3 . The test equipment system of  claim 2 , comprising voltage sense circuitry configured to measure a voltage signal across the first sense resistor in response to the current signal. 
     
     
         4 . The test equipment system of  claim 1 , wherein the auxiliary control circuit is configured to provide the auxiliary control signal as a voltage signal at the buffer control node. 
     
     
         5 . The test equipment system of  claim 1 , comprising a bypass circuit configured to selectively couple the buffer control node to the controller circuitry or to the auxiliary control circuit. 
     
     
         6 . The test equipment system of  claim 1 , wherein the output buffer circuitry comprises multiple buffers coupled to the DUT using respective sense resistors, and wherein one or more of the multiple buffers is selected to provide the DUT signal to the DUT interface node based on a characteristic of the force control signal at the buffer control node. 
     
     
         7 . The test equipment system of  claim 6 , wherein the multiple buffers comprise:
 a first buffer coupled to the DUT interface node using the first sense resistor; and   a second buffer coupled to the DUT interface node using the first sense resistor and a second sense resistor.   
     
     
         8 . The test equipment system of  claim 7 , comprising a second range switch configured to selectively couple a second driver input node to the second sense resistor. 
     
     
         9 . The test equipment system of  claim 8 , comprising:
 a third buffer coupled to the DUT interface node using the first sense resistor, the second sense resistor, and a third sense resistor; and   a third range switch configured to selectively couple the third sense resistor to receive the auxiliary control signal.   
     
     
         10 . The test equipment system of  claim 9 , wherein the third range switch comprises a portion of a first semiconductor die of a first semiconductor type, and wherein the first range switch and the second range switch comprise portions of a second semiconductor die of a second semiconductor type. 
     
     
         11 . A system for providing signals to, or receiving signals from, a device under test (DUT) at a DUT node, the system comprising:
 a first integrated circuit (IC) comprising a portion of a first semiconductor die of a first semiconductor type, the first IC comprising:
 a local controller configured to generate a local force control signal for a force-sense test system; and 
 a bypass circuit configured to provide a buffer control signal to an output buffer circuit based on the local force control signal from the local controller or on an auxiliary control signal from an external auxiliary controller for the same force-sense test system; and 
   a second IC comprising a portion of a second semiconductor die of a second semiconductor type, the second IC comprising:   the output buffer circuit;   a first sense resistor coupled to a first buffer and the DUT node; and   a first range switch coupled to the first sense resistor and an auxiliary driver input node, wherein the auxiliary driver input node is configured to receive an auxiliary drive signal from the external auxiliary controller.   
     
     
         12 . The system of  claim 11 , wherein the second IC comprises:
 a second sense resistor coupled to a second buffer and the first sense resistor; and   a second range switch coupled to the second sense resistor and a second driver input node, wherein the second driver input node is configured to receive the auxiliary drive signal from the external auxiliary controller.   
     
     
         13 . The system of  claim 11 , wherein the second IC comprises a third sense resistor; and
 wherein the first IC comprises a third range switch coupled to the third sense resistor and configured to receive the auxiliary drive signal from the external auxiliary controller.   
     
     
         14 . The system of  claim 13 , wherein the first IC comprises a fourth sense resistor and a fourth range switch;
 wherein the fourth sense resistor is coupled between the third and fourth range switches; and   wherein the fourth range switch is configured to receive the auxiliary drive signal from the external auxiliary controller.   
     
     
         15 . The system of  claim 11 , comprising the external auxiliary controller, wherein the external auxiliary controller comprises a calibration signal source configured to provide a calibration signal for calibrating the first sense resistor and the first buffer. 
     
     
         16 . A method for calibrating an automated test equipment (ATE) system, the method comprising:
 using a first current signal from an external auxiliary controller, determining a resistance of a first sense resistor, wherein the first sense resistor is coupled to a device under test (DUT) node of the system;   in response to a first voltage control signal from the external auxiliary controller, using one or more buffers in an output stage of the system to provide an output current at the DUT node via the first sense resistor;   measuring the output current at the DUT node; and   providing offset information about the one or more buffers in the output stage based on the measured output current.   
     
     
         17 . The method of  claim 16 , wherein determining the resistance of the first sense resistor includes:
 providing the first current signal to the first sense resistor using a first range switch;   measuring a first voltage across the first sense resistor using second and third switches; and   determining the resistance of the first sense resistor based on a magnitude of the first current signal and the measured first voltage;   wherein the second and third switches comprise a portion of a first semiconductor die of a first semiconductor type, and wherein the first range switch comprises a portion of a second semiconductor die of a second semiconductor type.   
     
     
         18 . The method of  claim 16 , wherein determining the resistance of the first sense resistor includes:
 closing a first range switch to provide a signal path from the external auxiliary controller to the first sense resistor, wherein the first range switch is coupled to a first buffer output of the one or more buffers in the output stage;   measuring a first voltage across the first sense resistor; and   determining the resistance using information about a magnitude of the first current signal and the measured first voltage.   
     
     
         19 . The method of  claim 18 , comprising determining a resistance of a second sense resistor using a second current signal from the external auxiliary controller, wherein the second sense resistor is coupled between the first sense resistor and a second buffer output of the one or more buffers in the output stage. 
     
     
         20 . The method of  claim 19 , wherein determining the resistance of the second sense resistor includes:
 opening the first range switch and closing a second range switch to provide a signal path from the external auxiliary controller to the second sense resistor;   providing a second current signal to a series combination of the first and second sense resistors using the second range switch;   measuring a second voltage across the series combination of the first and second sense resistors; and   determining the resistance using information about a magnitude of the second current signal and the measured second voltage.   
     
     
         21 . A method for calibrating an automated test equipment (ATE) system, the method comprising:
 using a first current signal from an external auxiliary controller, determining a resistance of a first sense resistor, wherein the first sense resistor is coupled to a device under test (DUT) node of the system;   generating a first force control signal using a local controller for a parametric measurement unit of the system;   receiving the force control signal at output buffer circuitry and, in response, providing a first DUT signal to a DUT at the DUT node, and measuring a voltage across the first sense resistor;   determining a current at the DUT node based on the measured voltage and the determined resistance of the first sense resistor; and   updating a characteristic of the local controller based on the determined current at the DUT node.   
     
     
         22 . The method of  claim 21 , wherein updating the characteristic of the local controller includes updating an offset for a digital-to-analog converter (DAC) circuit that is configured to control operation of the local controller.